The present invention relates to a plasma processing chamber for a plasma processing apparatus and, more in particular, to a plasma processing chamber with an improved utilizing-efficiency for plasma gases and an improved exhausting-efficiency for reaction gases.
The plasma processing chamber (hereinafter referred to as a plasma processing reactor) is as a reactor for use in low temperature plasma etching, low temperature plasma ashing, plasma CVD or the like and it includes various types, depending on the electrode structure, such as a coaxial feeding-type plasma processing reactor (cylindrical coaxial plasma processing reactor) and an opposed electrode-type plasma processing reactor using an Etch-tunnel.
The coaxial feeding-type plasma processing reactor is mainly composed of a cylindrical treatment chamber having a gas-introducing pipe and a gas-exhausting pipe connected to a vacuum system, an external electrode disposed in close contact with the outer periphery of the cylindrical treatment chamber and a cylindrical inner electrode disposed coaxially to the inside of the cylindrical treatment chamber at a predetermined gap therefrom and having a plurality of small apertures in the side wall thereof.
The opposed electrode-type plasma processing reactor using the Etch-tunnel has a structure in which a metal cylindrical member in the plasma processing reactor is not used as an inner electrode but used as an Etch-tunnel, and the electrodes are opposingly disposed in close contact with the outer periphery of the cylindrical treatment chamber.
Then, in any of the plasma processing reactors, wafers to be processed are contained to the inside of the cylindrical inner electrode or the Etch-tunnel and applied with plasma processing.
In the old plasma processing reactor, since the gas-introducing pipe and the gas-exhausting pipe are disposed externally to the cylindrical treatment chamber, such plasma processing reactor has the following drawbacks.
A plasma gas is generated between the external electrode and the cylindrical inner electrode in the coaxial feeding-type plasma processing reactor, or generated between external electrodes in the opposed electrode-type plasma processing reactor using the Etch-tunnel. Radicals which effectively act in the plasma processing, flow to the inside of the cylindrical inner electrode or Etch-tunnel, thereby contributing to the plasma processing. In this instance, since the flowing resistance upon passage through the cylindrical inner electrode or Etch-tunnel is not negligible, there is a drawback that a considerable amount of a plasma gas is exhausted directly to the gas-exhausting pipe connected with the vacuum system and can not be utilized effectively.
Further, the reaction exhaust gases generated upon plasma processing are removed by vacuum-sucking from the cylindrical inner electrode or Etch -tunnel by the gas-exhausting pipe. In this instance, since the flowing resistance upon passage through the cylindrical inner electrode or Etch-tunnel is not negligible, there is a drawback that the gas can not be exhausted efficiently.
An object of the present invention is to provide a plasma processing reactor with an improved utilizing-efficiency for plasma gases and an improved exhausting-efficiency for reaction exhaust gases.
As a result of an earnest study of the present inventors et al, it has been found that in a plasma processing reactor comprising: a cylindrical treatment chamber having a gas-introducing mechanism and a gas-exhausting mechanism and equipped with a heating mechanism at the periphery thereof; an external electrode disposed in close contact with the outer periphery of the cylindrical treatment chamber; and a metal cylindrical member disposed coaxially at a predetermined gap to the inner wall of the cylindrical treatment chamber and having a plurality of small apertures formed in the side wall thereof,
the gas-introducing mechanism being composed of a gas-introducing pipe having a plurality of gas-blowout means and disposed along the longitudinal direction of the cylindrical treatment chamber and a gas reservoir connected by way of a pipeline, and the gas-exhausting mechanism being composed of a gas-exhausting pipe having a plurality of gas-suction means and disposed along the longitudinal direction of the cylindrical treatment chamber and a vacuum means connected by way of a pipeline,
by disposing at least the gas-exhausting pipe to the inside of the metal cylindrical member, the utilization efficiency of the plasma gas and the exhaustion efficiency of the reaction exhaust gas can be improved in case carrying out the plasma processing in the said plasma processing reactor. The present invention has been accomplished based on the above mentioned finding.